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      <title>如何在 Nginx 中配置负载均衡的健康检查？ - 交互式测验</title>
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    <body>
      <div class="main-wrapper">
          <div class="quiz-container">
            <div class="quiz-header">
              <h1>如何在 Nginx 中配置负载均衡的健康检查？ - 交互式测验</h1>
              <p>检验你对文档内容的理解程度</p>
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            <div id="quiz-content">
                <div class="quiz-body">
                    <div class="progress-bar">
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      <script>
        const quizData = [
  {
    "question": "根据文档，开源版Nginx和商业版Nginx (Nginx Plus) 在实现健康检查功能方面的主要区别是什么？",
    "options": [
      "两者都内置了健康检查功能，但Nginx Plus的配置更复杂。",
      "开源版Nginx默认不带主动健康检查功能，需要编译第三方模块；而Nginx Plus内置了该功能。",
      "只有开源版Nginx支持通过第三方模块进行健康检查，Nginx Plus不支持。",
      "开源版Nginx的健康检查功能比Nginx Plus更强大和灵活。"
    ],
    "correctAnswerIndex": 1,
    "explanation": "文档明确指出，默认的开源Nginx不直接支持主动健康检查，需要借助第三方模块（如 `nginx-upstream-check-module`）并重新编译。相比之下，Nginx Plus提供了内置的健康检查功能，通过简单的 `health_check` 指令即可启用。",
    "source": "文档中「1. 使用 nginx 的健康检查功能」部分",
    "hint": "文档开头部分对比了两种Nginx版本的实现方式，其中提到了“默认的开源 Nginx 不直接支持主动健康检查”。"
  },
  {
    "question": "在使用 `nginx-upstream-check-module` 模块时，配置 `check interval=3000 rise=2 fall=5 timeout=1000;` 中的 `fall=5` 参数代表什么含义？",
    "options": [
      "后端服务器在连续5次检查都失败后，将被标记为不可用。",
      "健康检查请求在5毫秒后超时。",
      "后端服务器在连续5次检查都成功后，将被标记为健康。",
      "Nginx会尝试连接后端服务器5次，如果都失败则放弃。"
    ],
    "correctAnswerIndex": 0,
    "explanation": "根据文档中的参数说明，`fall=5` 定义了服务器被标记为不可用的条件。它指的是当Nginx对后端服务器的健康检查连续失败达到5次时，Nginx就会认为该服务器出现故障，并将其从负载均衡池中暂时移除。",
    "source": "文档中「2. 使用 nginx-upstream-check-module」部分的「参数说明」",
    "hint": "参数 `fall` 描述了服务器状态从“健康”变为“不健康”的条件。"
  },
  {
    "question": "在商业版Nginx (Nginx Plus) 的配置文件中，应该使用哪个指令来为 `upstream` 块启用内置的健康检查功能？",
    "options": [
      "check_status;",
      "enable_health_check true;",
      "health_check;",
      "monitor_upstream;"
    ],
    "correctAnswerIndex": 2,
    "explanation": "文档中的Nginx Plus配置示例非常清晰地展示了，在 `upstream` 块中，只需添加 `health_check;` 这一条指令，即可启用其内置的主动健康检查功能。",
    "source": "文档中「商业版 Nginx (Nginx Plus)」部分",
    "hint": "在Nginx Plus的配置示例代码中，`upstream backend` 块内有一个独立的指令用于激活此功能。"
  },
  {
    "question": "根据文档，要在开源版Nginx中成功使用 `nginx-upstream-check-module`，必须执行的关键前置步骤是什么？",
    "options": [
      "只需在 `nginx.conf` 配置文件中通过 `load_module` 指令加载即可。",
      "该模块是默认集成的，直接在配置中使用 `check` 指令就行。",
      "通过 `apt-get` 或 `yum` 等包管理器直接安装该模块。",
      "在编译Nginx源码时，通过 `--add-module` 参数将该模块一同编译进去。"
    ],
    "correctAnswerIndex": 3,
    "explanation": "文档强调，要在开源版Nginx中使用第三方模块，标准做法是在编译安装Nginx时，将该模块的源码作为参数（`--add-module`）添加到 `./configure` 命令中，使模块的功能被编译到Nginx可执行文件中。这与动态加载模块是不同的。",
    "source": "文档中「2. 使用 nginx-upstream-check-module」部分的「步骤概述」",
    "hint": "查阅文档中关于开源版的“步骤概述”，第一步就描述了编译前需要进行的操作。"
  },
  {
    "question": "假设一个后端服务器之前因故障被标记为不可用。在 `check rise=2 fall=5;` 的配置下，需要满足什么条件才能让该服务器重新被认为是健康的？",
    "options": [
      "该服务器只需要通过1次健康检查。",
      "该服务器需要在2秒内恢复正常响应。",
      "该服务器需要在连续5次健康检查中都通过。",
      "该服务器需要在连续2次健康检查中都通过。"
    ],
    "correctAnswerIndex": 3,
    "explanation": "参数 `rise=2` 定义了服务器从“不可用”状态恢复到“健康”状态的阈值。这意味着，之前被标记为不可用的服务器，必须连续通过2次健康检查，Nginx才会再次将其标记为健康，并重新向其转发请求。",
    "source": "文档中「2. 使用 nginx-upstream-check-module」部分的「参数说明」",
    "hint": "文档中对 `rise` 参数的解释是：“当后端服务器在连续的 rise 次检查中都通过时，标记为健康。”"
  },
  {
    "question": "在 `nginx-upstream-check-module` 的配置 `check interval=3000 timeout=1000;` 中，`interval` 和 `timeout` 参数的时间单位是什么？",
    "options": [
      "秒 (s)",
      "分钟 (min)",
      "微秒 (μs)",
      "毫秒 (ms)"
    ],
    "correctAnswerIndex": 3,
    "explanation": "文档的“参数说明”部分明确指出，`interval`（健康检查的时间间隔）和 `timeout`（健康检查的超时时间）这两个参数的单位都是毫秒。因此 `interval=3000` 代表3000毫秒，即3秒。",
    "source": "文档中「2. 使用 nginx-upstream-check-module」部分的「参数说明」",
    "hint": "仔细阅读文档中对 `interval=3000` 和 `timeout=1000` 的文字解释，里面明确提到了单位。"
  },
  {
    "question": "根据文档开篇的描述，在Nginx负载均衡中配置健康检查最核心的目的是什么？",
    "options": [
      "提高后端服务器的计算性能和响应速度。",
      "监控后端服务器健康状态，并在其不可用时自动将其从请求分发池中移除。",
      "加密Nginx与后端服务器之间的所有通信数据。",
      "详细记录每一条经过Nginx转发到后端服务器的请求日志。"
    ],
    "correctAnswerIndex": 1,
    "explanation": "文档第一段就开宗明义地指出，健康检查是“确保后端服务器健康状态和负载均衡效果的关键步骤”，其作用是“监控后端服务器的健康状态，并在服务器不可用时将其从负载均衡池中剔除”。这可以防止用户请求被发送到已经发生故障的服务器上，从而提高整个服务的可用性和稳定性。",
    "source": "文档开头的段落",
    "hint": "文档的第一句话就阐明了健康检查的“关键步骤”作用于什么方面。"
  }
];
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        let score = 0;
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          optionsListEl.innerHTML = '';
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                // 高亮正确答案
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                    child.style.borderColor = '#c3e6cb';
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                // 如果选错了，高亮错误选项
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            document.getElementById('quiz-footer').style.display = 'none';

            const correctCount = score;
            const totalQuestions = quizData.length;
            const answeredCount = userAnswers.filter(a => a !== null).length;
            const wrongCount = answeredCount - correctCount;
            const skippedCount = totalQuestions - answeredCount;
            const accuracy = totalQuestions > 0 ? Math.round((correctCount / totalQuestions) * 100) : 0;
            const errorRate = totalQuestions > 0 ? Math.round((wrongCount / totalQuestions) * 100) : 0;

            const finalScoreHtml =
                '<div class="final-score-container">' +
                '<h2>答题报告</h2>' +
                '<div class="score-summary">' +
                '<div class="score-card">' +
                '<h3>得分</h3>' +
                '<p>' + correctCount + ' / ' + totalQuestions + '</p>' +
                '</div>' +
                '<div class="score-card">' +
                '<h3>正确率</h3>' +
                '<p>' + accuracy + '%</p>' +
                '</div>' +
                '<div class="score-card">' +
                '<h3>错误率</h3>' +
                '<p>' + errorRate + '%</p>' +
                '</div>' +
                '<div class="score-card score-details">' +
                '<table>' +
                '<tr><td>正确</td><td>' + correctCount + '</td></tr>' +
                '<tr><td>错误</td><td>' + wrongCount + '</td></tr>' +
                '<tr><td>未答</td><td>' + skippedCount + '</td></tr>' +
                '</table>' +
                '</div>' +
                '</div>' +
                '<div class="report-actions">' +
                '<button id="review-btn">回顾测验</button>' +
                '<button class="primary" onclick="location.reload()">再试一次</button>' +
                '</div>' +
                '</div>';

            let reportEl = document.querySelector('.final-score-container');
            if (reportEl) {
                reportEl.remove();
            }
            quizContentEl.insertAdjacentHTML('beforeend', finalScoreHtml);
            document.getElementById('review-btn').addEventListener('click', reviewQuiz);
        }

        function reviewQuiz() {
            const reportEl = document.querySelector('.final-score-container');
            if (reportEl) {
                reportEl.remove();
            }

            document.querySelector('.quiz-body').style.display = 'block';
            document.getElementById('quiz-footer').style.display = 'flex';
            
            currentQuestionIndex = 0;
            loadQuestion();
            updateNavigationButtons(); // Ensure nav buttons are correctly displayed
        }

        // Event Delegation for options
        optionsListEl.addEventListener('click', (event) => {
            if (event.target && event.target.matches('li.option-item')) {
                // Check if the question has already been answered
                if (userAnswers[currentQuestionIndex] === null) {
                    const selectedIndex = parseInt(event.target.dataset.index, 10);
                    selectOption(selectedIndex);
                }
            }
        });

        prevBtn.addEventListener('click', goToPreviousQuestion);
        nextBtn.addEventListener('click', goToNextQuestion);
        hintBtn.addEventListener('click', showHint);
        
        // 初始加载
        loadQuestion();
      </script>
    </body>
    </html>
  